REPORT OF A CASEA 35-year-old white man with a 5-year history of slowly progressing nail dystrophy of the left index finger presented when his nail bed became tender. The patient denied a history of trauma to the finger. Physical examination revealed a vertical pigmented band, vertical ridging, and distortion of the lunula (Figure 1). A radiograph revealed a 5×5-mm, well-demarcated cyst in the midshaft of the distal phalanx (Figure 2).A total nail avulsion was performed. The proximal nail fold was reflected back to expose the tumor. Gross examination revealed a white, smooth, firm, well-circumscribed tumor that abutted on but was not attached to the underlying cortical bone (Figure 3). After blunt excision of the tumor, the base was curetted and the proximal nail fold was repaired. A normal nail plate regrew.Histopathologic examination of the tumor revealed mature lobules of cartilage with focal ossification around the periphery (Figure